Waste calcium carbide slags(CS),which are widely applied to desulfurisation,are not typically used in denitration.Herein,to well achieve waste control by waste,a facile and highefficiency denitration strategy is devel...Waste calcium carbide slags(CS),which are widely applied to desulfurisation,are not typically used in denitration.Herein,to well achieve waste control by waste,a facile and highefficiency denitration strategy is developed using KOH to modify the calcium carbide slags(KCS).Various KCS samples were investigated using a series of physical and chemical characterisations.The performance test results showed that the KOH concentration and reaction temperature are the main factors affecting the denitration efficiency of KCS,and CS modified with 1.5 mol/L KOH(KCS-1.5)can achieve 100% denitration efficiency at 300℃.Such excellent removal efficiency is due to the catalytic oxidation of the oxygen-containing functional groups derived from the KCS.Further studies showed that KOH treatment significantly increased the concentration of oxygen vacancies,nitro compounds,and basic sites of CS.This study provides a novel strategy for the resource utilisation of waste CS in the future.展开更多
采用低温固相燃烧法快速制备了一种具有{111}、{110}和{100}晶面的去顶角八面体LiNi_(0.08)Mn_(1.92)O_(4)(LNMO)正极材料,其高暴露{111}晶面可以减少充放电过程中Mn的溶解,面积相对较小的{110}和{100}晶面可增加Li^(+)快速扩散的通道....采用低温固相燃烧法快速制备了一种具有{111}、{110}和{100}晶面的去顶角八面体LiNi_(0.08)Mn_(1.92)O_(4)(LNMO)正极材料,其高暴露{111}晶面可以减少充放电过程中Mn的溶解,面积相对较小的{110}和{100}晶面可增加Li^(+)快速扩散的通道.测试结果表明,所合成的LNMO具有LiMn_(2)O_(4)特有的立方晶系结构,其颗粒尺寸为亚微米级.LNMO的高温电化学性能优异,在55℃,1和5 C的首次放电比容量分别为109.9和98.0 m Ah/g,分别循环300次后容量保持率为75.8%和80.5%;即使在55℃,10和15 C下分别循环1000次后仍具有48.4%和49.4%的容量保持率,而未掺杂的LiMn_(2)O_(4)于15 C循环1000次后容量损失高达98%.LNMO在55℃有较高的Li^(+)扩散系数(D=3.86×10^(-15)cm^(2)/s)和较小的电荷转移阻抗(循环前、后R_(ct)=158.0和279.8Ω)以及较低的表观活化能(E_(a)=17.63 k J/mol),说明Ni掺杂能够提高Li^(+)在尖晶石型LiMn_(2)O_(4)内的扩散速率及减小锂离子在脱嵌过程中的能垒,从而提高锂离子的扩散速率和倍率性能.对LNMO于55℃循环1000次后的极片进行X射线衍射(XRD)分析,发现LNMO电极材料的晶体结构基本保持不变,表明Ni掺杂提高了锰酸锂材料在55℃长循环过程中的晶体结构稳定性,有效抑制了Jahn-Teller效应及Mn的溶解,显著提升了其高温电化学性能.本工作为尖晶石LiMn_(2)O_(4)电极材料在高温方面的应用提供了借鉴.展开更多
基金supported by the National Natural Science Foundation of China(No.51968075)the Scientific Research Fund project of Yunnan Education Department(Nos.2022J0441 and 2022J0442)。
文摘Waste calcium carbide slags(CS),which are widely applied to desulfurisation,are not typically used in denitration.Herein,to well achieve waste control by waste,a facile and highefficiency denitration strategy is developed using KOH to modify the calcium carbide slags(KCS).Various KCS samples were investigated using a series of physical and chemical characterisations.The performance test results showed that the KOH concentration and reaction temperature are the main factors affecting the denitration efficiency of KCS,and CS modified with 1.5 mol/L KOH(KCS-1.5)can achieve 100% denitration efficiency at 300℃.Such excellent removal efficiency is due to the catalytic oxidation of the oxygen-containing functional groups derived from the KCS.Further studies showed that KOH treatment significantly increased the concentration of oxygen vacancies,nitro compounds,and basic sites of CS.This study provides a novel strategy for the resource utilisation of waste CS in the future.
文摘采用低温固相燃烧法快速制备了一种具有{111}、{110}和{100}晶面的去顶角八面体LiNi_(0.08)Mn_(1.92)O_(4)(LNMO)正极材料,其高暴露{111}晶面可以减少充放电过程中Mn的溶解,面积相对较小的{110}和{100}晶面可增加Li^(+)快速扩散的通道.测试结果表明,所合成的LNMO具有LiMn_(2)O_(4)特有的立方晶系结构,其颗粒尺寸为亚微米级.LNMO的高温电化学性能优异,在55℃,1和5 C的首次放电比容量分别为109.9和98.0 m Ah/g,分别循环300次后容量保持率为75.8%和80.5%;即使在55℃,10和15 C下分别循环1000次后仍具有48.4%和49.4%的容量保持率,而未掺杂的LiMn_(2)O_(4)于15 C循环1000次后容量损失高达98%.LNMO在55℃有较高的Li^(+)扩散系数(D=3.86×10^(-15)cm^(2)/s)和较小的电荷转移阻抗(循环前、后R_(ct)=158.0和279.8Ω)以及较低的表观活化能(E_(a)=17.63 k J/mol),说明Ni掺杂能够提高Li^(+)在尖晶石型LiMn_(2)O_(4)内的扩散速率及减小锂离子在脱嵌过程中的能垒,从而提高锂离子的扩散速率和倍率性能.对LNMO于55℃循环1000次后的极片进行X射线衍射(XRD)分析,发现LNMO电极材料的晶体结构基本保持不变,表明Ni掺杂提高了锰酸锂材料在55℃长循环过程中的晶体结构稳定性,有效抑制了Jahn-Teller效应及Mn的溶解,显著提升了其高温电化学性能.本工作为尖晶石LiMn_(2)O_(4)电极材料在高温方面的应用提供了借鉴.
